Conventionally, a type of conventional reciprocating refrigerant compressor has been proposed which includes a cylinder block having a cylinder bore, a piston for linear reciprocating motion within the cylinder bore, a compression chamber defined within the cylinder bore, a cylinder head formed with a suction chamber into which refrigerant gas is received for being drawn into the compression chamber, a valve plate formed with an inlet port for guiding the refrigerant from the suction chamber into the compression chamber, and an inlet valve for opening and closing the refrigerant inlet port.
The cylinder head is fixed to one end face of the cylinder block
FIG. 8 is a fragmentary expanded plan view of a valve plate of the conventional reciprocating refrigerant compressor.
The valve plate 402 is arranged between the cylinder head and the cylinder block, while the inlet valve 470 is arranged between the valve plate 402 and the cylinder block.
When the piston is moved from a top dead center position to a bottom dead center position, the inlet valve 470 opens into the cylinder bore 406, whereby the refrigerant flows from the suction chamber into the compression chamber via the inlet port 460.
When the piston is moved from the bottom dead center position to the top dead center position, the refrigerant inlet valve 470 is closed and the refrigerant is compressed within the compression chamber.
However, the cross-sectional area of the inlet port 460 is smaller than the cross-sectional area of the suction chamber, and therefore, when the piston is moved from the top dead center position to the bottom dead center position as described above, the flow of the refrigerant gas from the suction chamber is restricted at the inlet port 460, which prevents smooth flow of the gas into the compression chamber.
Further, since the cross-sectional area of the inlet port 460 is small and the load of the refrigerant gas acting on the inlet valve 470 is low when it is opened, the inlet valve 470 is delayed in timing of opening, and bursts open, which in combination with resilient physical properties of the inlet valve 470 causes self-induced vibration of the valve 470 This vibration produces a pulsation of the suctioned gas to cause resonance in an evaporator, thereby producing noise.
To improve the suction efficiency of the refrigerant gas, and suppress the self-excited vibration of the inlet valve 470, it is only required to increase the size of the inlet port 460 or the number of holes of the inlet port 460.
However, if the size of the inlet port 460 is increased, when the piston is moved from the bottom dead center position to the top dead center position as described above, the pressure of the refrigerant gas in the compression chamber acts on the inlet valve 470, and the pressure acting on this occasion can cause deformation or breakage of the inlet valve 470.
Further, to increase the number of holes of the inlet ports 460, additional space is necessary for the provision of additional holes, and at the same time, the inlet valve is increased in size and weight, which lowers the natural frequency of the inlet valve 470 to sometimes cause resonance of the same.
An object of the invention is to provide a reciprocating refrigerant compressor which is capable of preventing deformation and breakage of an inlet valve and resonance of the inlet valve when refrigerant is compressed, and at the same time, realizing improvement of the suction efficiency of the refrigerant and suppression of self-excited vibration of the inlet valve when the refrigerant is suctioned.